The present invention relates to piezoelectric systems, and more particularly to coriolis force driven piezoelectric gyroscope systems which each comprise two substantially orthogonally oriented elements projecting from a mass. Each substantially orthogonally oriented element has a pair of electrodes present thereupon, wherein the electrodes in a pair thereof are oriented substantially parallel to one another. The primary embodiment of said present invention system comprises one such system of substantially orthogonally oriented elements, with modified embodiments comprising a plurality of such systems in functional combination. In use a present invention system is caused to rotate about an axis oriented perpendicular to a plane formed by the substantially orthogonally oriented elements, while an extension inducing driving voltage is applied across a pair of electrodes on one substantially orthogonally oriented element. An output voltage, which is related to the rotation rate, is sensed across the pair of electrodes on the other orthogonally oriented element.
Piezoelectric gyroscopes are well known in the art. For instance, generally elongated rectangular solid shaped Piezoelectric gyroscopes which serve to produce a voltage at sensing electrodes thereof which is proportional to an angular rotation velocity of said piezoelectric-gyroscope about a longitudinally oriented axis therethrough are known, in which the mechanism of operation involves Coriolis force mediated flexure in a direction which is perpendicular to both said longitudinal axis, and a direction of an applied driving voltage effected flex.
One known embodiment of a piezoelectric gyroscope, as viewed in front elevational cross-section, typically has, at one longitudinally disposed side thereof, two vertically stacked, (ie. one atop the other), regions of vertically oriented polarized direction material sandwiched between driving voltage electrodes attached thereto at upper and lower surfaces. One of said vertically stacked regions of vertically oriented polarized direction material has an upward polarized direction and the other a downward polarized direction. On an opposite longitudinally disposed side thereof, and as viewed in side elevation there are present two adjacent regions of horizontally oriented polarized direction material, (ie. one in front of the other as viewed in frontal elevation), sandwiched between sensing voltage electrodes attached thereto at front and back vertically oriented surfaces. One said adjacent region of horizontally oriented polarized direction material having, as viewed from atop thereof, a horizontal laterally to the right projecting polarized and the other said adjacent region of horizontally oriented polarized direction material having a horizontal laterally to the left oriented polarized direction. That is, the polarized plane and polarized directions on said second longitudinally disposed side are simply rotated ninety (90) degrees, (eg. horizontally oriented), from the plane of the polarized directions, (eg. vertically oriented), on said first laterally disposed side about said longitudinally oriented axis therethrough.
Another prior art embodiment of a piezoelectric gyroscope is comprised of a long solid but flexible elongated rod with piezoelectric ceramics affixed thereto on side faces thereof. Said long solid but flexible rod can be triangular or rectangular in cross-section and have three or four electrodes mounted on side faces thereof. Where only three electrodes are present, both driving and sensing circuits share on of the electrodes. References which describe such piezoelectric gyroscope systems are:
xe2x80x9cVibrating Angular Rate Sensor May Threaten The Gyroscopexe2x80x9d, Gates, Electronics, 41, 103-134 (1968); and
xe2x80x9cPiezoelectric Vibratory Gyroscope Using Flexural Vibration Of A Triangular Barxe2x80x9d, Fujishima et al., IEEE 45th Annual Symp. On Frequency Control, 261-265 (1991).
Another prior art embodiment of a piezoelectric gyroscope is comprised of a solid but flexible, long, circular cross-section, piezoelectric elongated rod, with multiple electrodes affixed on the-outer surface thereof. Such an embodiment is described in U.S. Pat. No. 5,336,960 to Shimizi et al., which is titled xe2x80x9cGyroscope Using Circular Rod Type Piezoelectric Vibratorxe2x80x9d.
Another prior art embodiment of a piezoelectric gyroscope is comprised of a short flexible tubular shaped element, to an outer surface of which are affixed numerous piezoelectric ceramics. Application of driving voltage across some electrodes thereof cause a shape change from essentially circular cross section toward essentially elliptical cross-section, which shape change, in combination with rotation effected Coriolis force, causes an output voltage to appear at other of said electrodes. Such a gyroscopic system is described in xe2x80x9cThe Dynamics Of A Thin Film Piezoelectric Cylinder Gyroscopexe2x80x9d, Burdess, Proc. Inst. Mech. Engrs. 200 (C4), 271-280 (1986).
Yet another prior art embodiment of a piezoelectric gyroscope is described in an article by the inventor herein, titled xe2x80x9cA Cylindrical Shell Piezoelectric Gyroscopexe2x80x9d, Yang, Intl. J. of App. Electromagnetics and Mechanics, 8, 259-271, (1997). Said article describes a short tubular shaped piezoelectric gyroscope system in which radial and torsional vibration modes are utilized to realize a rotation detecting system.
Disclosed in a related Application by the present Inventor, (Ser. No. 09/271,791), now U.S. Pat. No. 6,140,748, is a piezoelectric gyroscope system comprising a generally longitudinally elongated three dimensional mass of piezoelectric material having first and second longitudinally disposed sides, said piezoelectric gyroscope system being distinguished in that a sensing electrode is present at one terminal end thereof, said sensing electrode being affixed so that it is oriented other than on a longitudinally oriented side of said piezoelectric gyroscope. Typically, said terminal end of said present invention piezoelectric gyroscope system, whereat said sensing electrode is affixed, is accurately described as oriented in a direction perpendicular to the direction of longitudinal elongation, and the generally longitudinally elongated three dimensional mass of piezoelectric material is a selected to be of a rectangular solid shape. Said invention couples the voltage amplification benefits of piezoelectric (Rosen) transformers to the angular velocity measuring capabilities of piezoelectric-gyroscopes, by placing a sensing electrode in a piezoelectric-gyroscope much as is done in piezoelectric-transformers, (eg. as viewed in elevation, at a vertically oriented end of a longitudinally disposed side of a present invention piezoelectric-gyroscope at which is present two regions of horizontally longitudinally oriented polarized direction material). That is, the two sensing electrodes in a conventional piezoelectric-gyroscope, described above as adjacent to regions of horizontally, laterally oriented polarized direction material, (ie. one in front of the other as viewed in frontal elevation), sandwiched between sensing voltage electrodes attached thereto at front and back surfaces, are, in the preferred embodiment of the present invention, replaced by a single electrode at a vertically oriented end of the longitudinally disposed side of the present invention piezoelectric-gyroscope at which is present the two adjacent regions of horizontally longitudinally oriented polarized direction material. Said single electrode can reference to one of the driving electrodes, or to a second sensing electrode. A preferred embodiment of said related invention Piezoelectric Gyroscope, which serves to couple the voltage amplification benefits of piezoelectric (Rosen) transformers to the angular velocity measuring capabilities of conventional piezoelectric gyroscopes, can be described as comprising a generally elongated, typically rectangular solid shaped block of piezoelectric material having first and second longitudinally disposed sides and a longitudinally oriented axis which projects essentially centrally therethrough from said first longitudinally disposed side to said second longitudinally disposed side thereof. At the first longitudinally disposed side thereof there are present two, vertically stacked, regions of oppositely oriented polarized direction material sandwiched between driving voltage electrodes. One of said vertically stacked regions of oppositely oriented polarized direction material has, for instance, an xe2x80x9cupwardxe2x80x9d polarized direction and the other a xe2x80x9cdownwardxe2x80x9d polarized direction. And on the second longitudinally disposed side thereof there are two adjacent regions of oppositely oriented polarized direction material, one said adjacent region of oppositely oriented polarized direction material having, for instance, a longitudinally xe2x80x9cto the rightxe2x80x9d projecting polarized and the other said adjacent region of oriented polarized direction material having a longitudinally xe2x80x9cto the leftxe2x80x9d oriented polarized direction. The plane of the polarized directions on said second longitudinally disposed side is rotated ninety (90) degrees from the plane of the polarized directions on said first longitudinally disposed side. Said piezoelectric-gyroscope further has a sensing electrode present at a vertically oriented end of the second longitudinally disposed side of the present invention piezoelectric-gyroscope.
In another Patent Application by the same Inventor, Ser. No. 09/659,624, there is described a piezoelectric gyroscope system comprising a generally longitudinally elongated essentially tubular structure presenting with inner and outer annular region defining surfaces and first and second longitudinally disposed ends, said piezoelectric gyroscope system being distinguished in that:
a. an electrode is present on the inner surface thereof, and
b. in that there are present four electrodes on the outer surface thereof spaced at substantially ninety degree intervals, and
c. in that said generally longitudinally elongated essentially tubular structure, the annular region thereof of which is made of piezoelectric material which is radially polarized.
Note that the electrode which is present on the inner surface of the present invention piezoelectric gyroscope system is present to functionally serve as a second plate with respect to driving electrodes Said electrode is typically present on substantially the entire inner surface, which is to be interpreted based upon said functional purpose of said xe2x80x9cinner electrodexe2x80x9d. Functionally, said inner electrode can be primarily present only directly opposed to said driving and sensing electrodes.
It is noted that the four electrodes on the outer surface thereof can alternatively be described as each being present in a separate quadrant, (as the piezoelectric gyroscope generally longitudinally elongated essentially tubular structure is viewed in cross-section), with at least the two xe2x80x9cdriving electrodesxe2x80x9d thereof being substantially oriented at substantially 180 degrees with respect to one another. The sensing electrodes are, however, also preferably oriented at substantially 180 degrees with respect to one another to optimize sensed voltage magnitude.
In use said piezoelectric gyroscope is caused to rotate at an angular rotation velocity about said longitudinally oriented axis which projects essentially centrally therethrough from said first longitudinally disposed end to said second longitudinally disposed end, and a flex effecting voltage is applied across two electrodes oriented at substantially 180 degrees with respect to one another, (ie. driving electrodes), while an output voltage is sensed at the other two electrodes, (ie. sensing electrodes). The end result is that when both:
angular rotation velocity about said longitudinally oriented axis which projects essentially centrally therethrough from said first longitudinally disposed end to said second longitudinally disposed end, and
flex effecting voltage is applied across the driving electrodes,
it occurs that, through the mechanism of Coriolis force, another flex perpendicular to the voltage effected flex occurs and is related to said angular rotation velocity about said longitudinally oriented axis therethrough, appears across the two sensing electrodes which are oriented such that the xe2x80x9caxisxe2x80x9d thereof, (ie. the direction through the sensing electrodes and perpendicular thereto), is substantially perpendicular to both the axis of rotation and the xe2x80x9caxisxe2x80x9d of the driving electrodes.
It is also disclosed that the preferred piezoelectric material from which the generally longitudinally elongated essentially tubular structure is made is ceramic, because, as alluded to, ceramic is inherently isotropic and it is relatively easy to induce polarized regions therein. However, use of any functional material is to be considered within the scope of the present invention, with another very relevant candidate being, for instance, lithium niobate.
A tuning-fork shaped piezoelectric gyroscope system can also be formed from said essentially tubular structure made of piezoelectric material presenting with inner and outer annular region defining surfaces, first and second legs thereof being projected from a base, preferably formed from a substantially xe2x80x9cUxe2x80x9d shape tubular structure, said tuning-fork shaped piezoelectric gyroscope system again being distinguished in that:
an electrode is present on the inner surface thereof, and
in that there are present two electrodes on the outer surface of each leg, said two electrodes being positioned at substantially 180 degrees to one another and such that an axis through the electrodes on one leg is oriented essentially 90 degrees to an axis through the electrodes on the other leg, and
in that said tubular structure annular region piezoelectric material is substantially radially polarized;
such that causing said piezoelectric gyroscope to rotate about said base and applying a flex effecting voltage across two xe2x80x9cdrivingxe2x80x9d electrodes oriented at substantially 180 degrees with respect to one another on one leg causes an output voltage to develop which can be sensed at the two xe2x80x9csensingxe2x80x9d electrodes on the other leg.
A method of monitoring an angular rotation velocity comprises the steps of:
a. providing a present invention piezoelectric gyroscope as just described;
said method further comprising in a functional order the steps of:
b. causing said piezoelectric gyroscope to rotate about a longitudinally oriented axis, (eg. an axis which projects essentially centrally therethrough from said first longitudinally disposed end to said second longitudinally disposed end and applying a flex effecting voltage across two electrodes oriented at substantially 180 degrees with respect to one another, (ie. driving electrodes), such that an output voltage is developed at the other two electrodes, (ie. driving electrodes).
c. monitoring said developed output voltage at said other two electrodes, (ie. sensing electrodes), said monitored output voltage being related to said angular velocity of rotation about said longitudinally oriented axis which projects essentially centrally therethrough from said first longitudinally disposed end to said second longitudinally disposed end.
Generally, in use Piezoelectric gyroscopes are caused to rotate at an angular rotation velocity about a typically longitudinally oriented axis, which projects essentially centrally therethrough from said first longitudinally disposed, side to said second longitudinally disposed side, and a flex effecting voltage is applied across the driving electrodes while an output voltage is sensed across said sensing electrodes. When both angular rotation velocity about said longitudinally oriented axis therethrough, and flex effecting voltage is present across the driving electrodes, it occurs that, (through the mechanism of Coriolis force), a voltage appears at the sensing electrodes which is related to said angular rotation velocity about said longitudinally oriented axis therethrough. Where the angular rotational velocity about said longitudinally oriented axis therethrough is at least an order of magnitude less than is the natural vibrational frequency of the piezoelectric gyroscope material, the output voltage at the sensing electrodes is typically directly proportional to said angular rotational velocity.
As mentioned, it is also known that materials which are well suited for use in Piezoelectric-transformers and gyroscopes are ceramics in which can be effected regions of poled direction by a xe2x80x9cPoling procedurexe2x80x9d. Ceramics are inherently isotropic so, that polarization can be determined by application of an electric field across the materials in excess of the coercive field thereof, (which is typically on the order of 1 MV/m), while raising the temperature of the material above the Curie point, and then cooling the material below this point to lock-in the induced domain structure. A reference which describes this procedure is titled xe2x80x9cSmart Structures and Materialsxe2x80x9d, Culshaw, Artech House, (1996).
A search of Patents which describe piezoelectric gyroscopes provided nothing obviating of the present invention system. Identified Patents are:
A Patent to Wirt, U.S. Pat. No. 5,495,760 describes a gyroscope with one or more drive cylinders which have single electrodes on the inside and on the outside diameters.
A Patent to Kumada, U.S. Pat. No. 5,912,528 describes a vibrating gyroscope which includes a ring-shaped vibrator having a node.
A Patent to Kananami et al., U.S. Pat. No. 5,874,674 describes a piezoelectric vibratory gyroscope having non-parallel sides.
Additional known Patents which describe angular or rotation measuring systems comprised of piezoelectric materials are:
U.S. Pat. No. 3,143,889 to Simmons et al., which provides for electrodes to be present on a piezoelectric material on top and bottom surfaces and on front and back surfaces.
U.S. Pat. No. 3,258,617 to Hart describes a piezoelectric system which positions sensing electrodes, (see (23) and (24) of FIG. 2 therein), at both the ends of a preferably rectangular shaped mass of piezoelectric material.
U.S. Pat. No. 3,141,100 to Hart describes a rather complex system comprised of a plurality of crystal quartz elements.
U.S. Pat. No. 5,837,895 describes a vibrating gyroscope including a piezoelectric substrate having two divided electrodes on one main surface, and a single electrode on the other main surface.
U.S. Pat. No. 5,942,839 describes a piezoelectric vibratory gyroscope having three parallel vibrator arms.
U.S. Pat. No. 5,912,524 to Ohnishi et al. describes a vibratory gyroscope.
U.S. Pat. No. 5,847,487 to Maeno describes a cross-shaped vibration gyroscope.
U.S. Pat. No. 5,945,600 to Touge et al., describes an angular rate detector.
U.S. Pat. No. 5,767,405 to Bernstein et al., describes a tuning fork gyroscope.
U.S. Pat. No. 5,691,595 to Tomikawa et al., describes a vibratory gyroscope including a planar elastic vibrator having vibrator piezoelectric material layers on the front and back sides.
Additionally:
U.S. Pat. No. 3,736,446 to Berlincourt et al., describes a piezoelectric transformer with an electrode (17) at an end of a preferably rectangular shaped mass of piezoelectric material. This Patent also shows a system structure with various regions of polarized direction material present therein. Reference to FIG. 1 therein shows two regions (13) and (14) of oppositely directed vertical polarized at the leftmost side thereof as viewed in said FIG. 1, and with a region of horizontally polarized material at the right side (12) as so viewed.
U.S. Pat. No. 5,504,384 to Lee et al. shows another piezoelectric transformer with electrodes (11) and (12) at ends of an essentially rectangular shaped block of piezoelectric material. Also described are various regions of polarized material present therein. Reference to FIG. 2 in said 384 Patent shows horizontally oppositely directed regions of piezoelectric material at laterally disposed ends of the essentially rectangular shaped block of piezoelectric material, with oppositely directed vertically poled regions of piezoelectric material centrally located therewithin.
Articles which describe conventional Piezoelectric transformers and gyroscopes are:
A paper titled xe2x80x9cPiezoelectric-Ceramic Cylinder Vibratory Gyroscopexe2x80x9d, by Abe et al., Jpn. J. Appl. Phys., Vol. 31, (1992), describes a piezoelectric gyroscope with a cylindrical structure.
Another paper titled xe2x80x9cConsideration On Equivalent Mechanical Circuits For Vibratory Gyroscopexe2x80x9d, by Kudo et al., IEEE Ultrasonics Symp., (1990) describes equations of gyro-motion and proposes many vibratory gyroscopes including one utilizing rotation motion in a double resonate vibrator system.
Another paper titled xe2x80x9cPiezoelectric Vibratory Gyroscope Using Flexural Vibration Of A Triangular Barxe2x80x9d, by Fujishima et al., IEEE Forth-Fifth Annual Symp. on Freq. Control, (1991), describes basic principals of a piezoelectric vibratory gyroscope and discloses development of a unique triangular bar flexural vibratory piezoelectric gyroscope.
A paper titled xe2x80x9cMathematical Theory Of The Fork-Type Wave Gyroscopexe2x80x9d, Ulitko, IEEE International Frequency Control Symposium, (1995) describes operation of Fork-type gyroscopes.
Another paper which describes Fork-type Vibratory Gyroscopes is titled xe2x80x9cLiTaO3 Crystal Fork Vibratory Gyroscopexe2x80x9d by Wakatsuki et al., IEEE Ultrasonics Symposium, (1994).
Another paper titled xe2x80x9cFinite Element Analysis Of A Quartz Angular Rate Sensorxe2x80x9d, ANSYS Conference Proceedings, 3.35-48, (1989) is further cited as is a paper titled xe2x80x9cFinite Element Analysis Of Single Crystal Tuning Forks For Gyroscopesxe2x80x9d, by Kudo et al., IEEE Intl. Freq. Control Symp., (1996), describes the results of applying finite element analysis to tuning fork gyroscopes.
Papers which describe piezoelectric gyroscopes with small resonant frequencies are xe2x80x9cA Review of Vibratory Gyroscopexe2x80x9d, Burdess et al., Engineering Science and Education Journal, pp. 249-254, (1994); and xe2x80x9cMicromachined Gyroscopesxe2x80x9d, Soderkvist, Sensors and Actuators A, 43, pp 65-71, (1994).
Discussion of dependence of the relationship of operating characteristics of piezoelectric gyroscopes to physical and geometrical parameters thereof, explicitly shown in simple expressions, are found in:
xe2x80x9cA Coupled Electromechanical Model of an Imperfect Piezoelectric Vibrating Cylindrical Gyroscopexe2x80x9d, Loveday, J. Intelligent Material Systems and Structures, 7, 44-53, (1996);
and in
xe2x80x9cFinite Element Simulation of Piezoelectric Vibrator Gyroscopesxe2x80x9d, Kagawa, IEEE Trans. on Ultrasonic Ferroelectrics and Freq. Control, 43, pp. 509-518, (1996).
Rotation induced frequency shift, which can be linear with respect to rotation rate and can therefore be used to detect the rotation rate, are further discussed in:
xe2x80x9cGyroscope Effect in Surface Acoustic Wavesxe2x80x9d, Lao, Proc. Ultrasonics Symp. pp. 678-691, (1980);
xe2x80x9cCirculating Flexural Wave Rotation Rate Sensorxe2x80x9d, Tiersten, Proc. IEEE Ultrasonics Symposium, pp. 163-166, (1981);
xe2x80x9cA Rotation Rate Sensor Based Upon a Rayleigh Resonatorxe2x80x9d, Clark and Burdess, ASME J. App. Mech., 61, pp. 139-143, (1994).
Other Articles of which the Applicant is aware, which describe Piezoelectric Gyroscopes which are more complex that the present invention systems are:
xe2x80x9cVibrating Angular Rate Sensor May Threaten Gyroscopexe2x80x9d, Gates, Electronics, 41, pp.130-134, (1968);
xe2x80x9cPiezoelectric Vibratory Gyroscope Using Flexural Vibration of a Triangular Barxe2x80x9d, Fujishima et al., Proc. IEEE 45th Annual Symp. on Frequency Control, pp. 261-265, (1991);
xe2x80x9cAnalysis on Vibrating Piezoelectric Beam Gyroscopexe2x80x9d, Chou et al., Int. J. of App. Electromagnetics in Materials, 2, pp. 227-241, (1991);
xe2x80x9cPiezoelectric Beams and Vibrating Angular Rate Sensorsxe2x80x9d, IEEE Trans. Ultrasonics, Ferroelectrics, and Freq. Control, 38, pp. 271-280, (1991);
xe2x80x9cThree-Dimensional Finite Element Calculations of an Experimental Quartz Resonator Sensorxe2x80x9d, Reese et al., Proc. IEEE Ultrasonics Symp. pp419-422, (1989);
xe2x80x9cEnergy Trpping of Thickness Shear Vibrations Excited by Parallel Electric Field and its Applications to Piezoelectric Vibratory Gyroscopesxe2x80x9d, Abe et al., Proc. IEEE Ultrasonics Symp., pp. 467-471, (1998);
xe2x80x9cAnalysis of Ceramic Thickness Shear Piezoelectric Gyroscopesxe2x80x9d, Yang, J. Accoust. Soc. Am., 102 pp. 3542-3548, (1997);
xe2x80x9cA Vibrating Piezoelectric Ceramic Shell as a Rotation Sensorxe2x80x9d, Yang et al., Smart Materials and Structures, 9, pp. 445-451, (1998);
xe2x80x9cThe Dynamics of a Thin Piezoelectric Disk Gyroscopexe2x80x9d, Burdess et al., IEEE Trans. on Aerospace and Electronic Systems, AES-22, pp. 410-418, (1986);
xe2x80x9cThe Dynamics of a Piezoelectric Cylinder Gyroscopexe2x80x9d, Burdess et al., Proc. Inst. Mech. Engrs., 200 (C4), pp. 271-280, (1986);
xe2x80x9cOne-Dimensional Equations for a Piezoelectric Ring and Applications in a Gyroscopexe2x80x9d, Yang et al., IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control ????;
xe2x80x9cAcoustic Fields and Waves in Solidsxe2x80x9d, Vol. 1, John Wiley and Sons, New York, (1973) pp. 357-382;
xe2x80x9cDesign or Resonant Piezoelectric Devicesxe2x80x9d, Holland et al., MIT Press, Cambridge, (1969).
Even in view of the identified known prior art, there remains need for new piezoelectric gyroscope systems which provide angular velocity measuring capability.
The present invention is a piezoelectric gyroscope system comprising two substantially orthogonally oriented elements, (refered to in the Detailed Description Section of this Disclosure more simply as xe2x80x9crodsxe2x80x9d), each of which project from a mass. Each said substantially orthogonally oriented element has a pair of electrodes present thereupon, with the electrodes in a pair thereof being oriented substantially parallel to one another. In use said piezoelectric system is caused to rotate about an axis oriented perpendicular to a plane formed by said two substantially orthogonally oriented elements while a extension inducing driving voltage is applied across a pair of electrodes on one thereof, to the end that an output voltage which is related to the rotation rate, is sensed across the pair of electrodes on the other substantially orthogonally oriented element.
A preferred arrangement provides that the rotation about the axis oriented perpendicular to a plane formed by said two substantially orthogonally oriented elements be centered at the mass from which the two substantially orthogonally oriented elements project.
The present invention further comprises a multiple piezoelectric gyroscope system comprising a plurality of piezoelectric gyroscope systems, wherein each thereof comprises:
first and second substantially orthogonally oriented elements projecting from a mass, each said substantially orthogonally oriented element having a pair of electrodes present thereupon, wherein each electrode in a pair thereof are oriented substantially parallel to one another; such that in use said piezoelectric system is caused to rotate about an axis oriented perpendicular to a plane formed by said two substantially orthogonally oriented elements while an extension inducing driving voltage is applied across a pair of electrodes on one thereof, to the end that an output voltage which is related to the rotation rate, is sensed across the pair of electrodes on the other substantially orthogonally oriented element. The piezoelectric gyroscope system is oriented such that the first and second substantially orthogonally oriented elements oft each thereof are all in a common plane; and the electrodes on the first of each said substantially orthogonally oriented elements in each said piezoelectric gyroscope have electrical connection with the first substantially orthogonally oriented elements on the other piezoelectric gyroscopes. Further, the electrodes on the second of each said substantially orthogonally oriented elements in each said piezoelectric gyroscope have electrical connection with the second substantially orthogonally oriented elements on the other piezoelectric gyroscopes. In use said multiple piezoelectric system is caused to rotate about an axis oriented perpendicular to the common plane formed by all said two substantially orthogonally oriented elements, while an extension inducing driving voltage is applied across all electrically interconnected electrode pairs on the first elements thereof, to the end that an output voltage which is related to the rotation rate, is sensed across the electrically interconnected electrode pairs on the second substantially orthogonally oriented elements thereof.
Said multiple piezoelectric gyroscope system preferably comprises four piezoelectric gyroscope systems, said four piezoelectric gyroscope systems being oriented with respect to one another such that the masses thereof are positioned as the four corners of a rectangle, and such that the orthogonally related elements are oriented along sides thereof. The preferred rectangle is a square.
A method of developing a voltage which is proportional to a rotation rate, comprises the steps of:
a. providing a piezoelectric gyroscope system comprising two substantially orthogonally oriented elements projecting from a mass as described above;
b. causing said piezoelectric gyroscope to rotate about an axis oriented perpendicular to a plane formed by said two substantially orthogonally oriented elements;
c. applying an extension inducing driving voltage is applied across a pair of electrodes on one substantially orthogonally, oriented element;
to the end that an output voltage which is related to the rotation rate, is sensed across the pair of electrodes on said other substantially orthogonally oriented element.
A method of developing a voltage which is proportional to a rotation rate, comprises the steps of:
a. providing at least two piezoelectric gyroscope systems as described above and functionally interconnecting them,
b. causing said piezoelectric gyroscope which is comprised of at least two piezoelectric gyroscope systems, to rotate about an axis oriented perpendicular to a plane formed by said two substantially orthogonally oriented elements;
c. applying an extension inducing driving voltage across a pair of electrodes on one substantially orthogonally oriented element of each of said at least two piezoelectric gyroscope systems;
to the end that an output voltage which is related to the rotation rate, is sensed across functionally interconnected pairs of electrodes on said other substantially orthogonally oriented elements of each of said at least two piezoelectric gyroscope systems.
The present invention will be better appreciated, by reference to the Detailed Description Section of this Disclosure, with appropriate reference to the accompanying Drawings.